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Friday, April 13, 2012

Assembling of three-dimensional crystals by optical depletion force induced by a single focused laser beam

Hai-Dong Deng, Guang-Can Li, Hai-Ying Liu, Qiao-Feng Dai, Li-Jun Wu, Sheng Lan, Achanta Venu Gopal, Vyacheslav A. Trofimov, and Tatiana M. Lysak

We proposed a method to assemble microspheres into a three-dimensional crystal by utilizing the giant nonequilibrium depletion force produced by nanoparticles. Such assembling was demonstrated in a colloid formed by suitably mixing silica microspheres and magnetic nanoparticles. The giant nonequilibrium depletion force was generated by quickly driving magnetic nanoparticles out of the focusing region of a laser light through both optical force and thermophoresis. The thermophoretic binding of silica beads is so tight that a colloidal photonic crystal can be achieved after complete evaporation of solvent. This technique could be employed for fabrication of colloidal photonic crystals and molecular sieves.

DOI

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